This invention relates to generally to the leaching of a base metal.
The invention relates to a hydrometallurgical method for heap leaching of copper from principally sulphide minerals such as chalcocite, covellite, bornite and chalcopyrite, or a mixed sulphide with copper oxide mineral. These applications are however exemplary only and are non-limiting for the principles of the invention may be used for the recovery of base metals such as nickel from nickel sulphide minerals e.g. pentlandite and millerite, and for the recovery of zinc from zinc sulphide minerals. The invention is described hereinafter with reference to the use of a high chloride mediated, high solution potential, pre-treatment step for heap leaching of run-of-mine (ROM) or crushed ore.
An object of the invention is to increase the oxidation rate of sulphide minerals or mixed sulphide and oxide minerals during a pre-treatment step prior to active heap irrigation, and thereby provide improved metal recovery in a shorter leach cycle and, additionally, to address the operational cost of a heap leach by reducing aeration requirements.